A clock and data recovery (CDR) chip is utilized to capture a clock signal from a received data signal. Data recovery includes regenerating the data signal utilizing a phase-comparison circuit to make sure that the clock signal is in phase synchronization with the data signal. CDR chips are widely used in optical transceivers, telecommunications and wireless products. Generally, CDR chips are used in small form-factor (SFF) modules based on the Lucent optical connector (LC) to replace discrete optical devices for the extraction of clock and recovery data. Rx_lol and mod_nr represent two state flag bits of the CDR chip. When there is no data input to the CDR chip, the state flag bit of rx_lol continuously varies between “0” and “1”. As a result, the optical transceiver state bit of rx_lol is unstable. Because rx_lol is a trigger signal for mod_nr, the state bit of mod_nr also becomes unstable, thereby resulting in an unstable output display status of the optical transceiver that will influence the estimation of the working condition of the optical transceiver.